During various types of ophthalmic surgical procedures temporary expansion of the pupillary area of the human eye, and maintenance of the expanded pupillary opening, is desirable in order to minimize various types of trauma or surgical incisions. One such surgical procedure typically involves an incision in the limbus area to gain access to the lens of the eye in order to remove a cataractous lens and replace the removed lens with commercially available intraocular lenses to be implanted within the posterior chamber, behind the iris.
Heretofore, such surgery typically involved the formation of a semicircular groove in and about the limbus area of the eye, which the surgeon then uses to cut through the eye forming a flap to provide access to the anterior chamber of the eye in order to remove the cataract lens. The formation of this corneal flap, which is lifted to provide access to the lens, requires a large incision involving numerous sutures and care during closure.
Alternate techniques have in recent years involved attempts to reduce incision size which has been facilitated by the use of emulsification devices in combination with foldable or reduced dimension implants. While this is an advance in the surgical procedure for cataract removal, it usually requires a dilated pupil to prevent interference with emulsification of the cataract lens. While nonsurgical techniques to dilate the pupil are typically employed, frequently mechanical expansion is required to maintain the enlarged pupil area throughout the surgical procedure.
A variety of devices have heretofore been suggested for such mechanical expansion of the pupil but many of them result in inadequate working space and frequently distort the postoperative condition of the iris.
Examples for mechanically expanding the pupil have included engaging the edges of the iris with hooks, pegs or stretching devices which invariably result in permanent deformation of the iris. Preplaced suturing followed by incisions in the iris have also been used as a means to expand the pupil. Since it is desirable to avoid unnecessary incisions this has not been met with popularity.
Another such device is illustrated in U.S. Pat. No. 4,782,820. As pointed out in this disclosure, it is desirable to expand the normal pupil area of approximately three millimeters to as large as seven to nine millimeters during operative procedures. The referenced prior art device discloses a retaining ring formed of a flexible arcuate body having a U-shaped cross section forming a side wall intended to receive the edges of the iris. A drawstring is provided to manipulate the ring so that it can contract to a size which can facilitate placement within the unexpanded pupil area and then be permitted to expand, while engaging the edges of the iris. The use of such a device however would be difficult and impracticable as it requires contraction of the ring to a size likely less than one millimeter in diameter for proper placement within the unexpanded pupil, and subsequent expansion to the required seven to nine millimeter diameter. In addition, proper placement within the unexpanded pupil appears exceedingly difficult while simultaneously trying to maintain tension on the drawstring structure.
It is accordingly a principal object of the present invention to provide a simple and easy to use device for application in ophthalmic surgery, which overcomes the disadvantages of the prior art pupillary expansion techniques while permitting cataract or other ophthalmic surgery through minimal incision procedures.
A more specific object of the present invention is to provide a pupil expander which can be easily deformed for placement within the eye through a small eye incision for engagement with the iris to accomplish pupil expansion.
Yet a further object of the present invention is to provide a human eye pupil expander made of resilient polymethylmethacrylate material to permit spring-like performance so that it can be collapsed about a hinge or pivot point for insertion through a small opening.
A still further object of the present invention is to provide a device which is capable of mechanically enlarging the pupil of a human eye without causing permanent distortion of the iris.